A thermowax switching valve is often employed as a valve for switching the flow of fluid in a fluid circuit such as a coolant circuit of a water-cooled engine. The thermowax switching valve is selectively opened and closed by expansion and contraction accompanying melting and solidification of the thermowax sealed inside of a case. A heater for heating the thermowax is often provided to force such a thermowax switching valve to open as needed.
A control device for a vehicle including such a thermowax switching valve with a heater has been proposed as disclosed in Patent Document 1. The vehicle disclosed in Patent Document 1 includes the above-mentioned thermowax switching valve in a hydraulic circuit of the engine, and a PTC heater for heating the thermowax of the switching valve.
The control device for a vehicle disclosed in Patent Document 1 includes an oil temperature sensor that detects the oil temperature in the hydraulic circuit, and estimates the temperature of the thermowax based on the oil temperature detected by the oil temperature sensor. When opening the switching valve, the PTC heater keeps being energized until a sensor value of the oil temperature sensor becomes higher than the melting temperature of the thermowax.